TELLURIUM  ALLOYS 


BY 


LOTTIE  ELLA  MUNN 

A.  B.  Baldwin  Wallace  College,  1917 


THESIS 

SUBMITTED  IN  PARTIAL  FULFILLMENT  OF  THE  REQUIREMENTS 
FOR  THE  DEGREE  OF  MASTER  OF  SCIENCE  IN  CHEMISTRY 
IN  THE  GRADUATE  SCHOOL  OF  THE  UNIVERSITY 
OF  ILLINOIS,  1922 


( 


URBANA,  ILLINOIS 


UNIVERSITY  OF  ILLINOIS 


THE  GRADUATE  SCHOOL 


May  22, 192-2 

I HEREBY  RECOMMEND  THAT  THE  THESIS  PREPARED  UNDER  MY 

SUPERVISION  BY LOT-TIE-  ELLA41UU3I 

ENTITLED TELLURIUM  ALLOYS „ 


BE  ACCEPTED  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR 
THE  DEGREE  OF Master  of  Science 


Recommendation  concurred  in* 


Committee 

on 

Final  Examination* 


499uf 


*Required  for  doctor’s  degree  but  not  for  master’s 


.... 


. 


Table  of  Contents. 


I.  Introduction 
II.  Experimental  Work 
III.  Results 

IV.  Attempt  to  Analyze  Lead- Tellurium  Mixtures 
V.  Summary 
VI.  Bibliography 
VII.  Acknowledgment 


1. 


o. 


9. 


14. 

16. 


17. 


13. 


Digitized  by  the  Internet  Archive 

in  2015 


https://archive.org/details/telluriumalloysOOmunn 


1 


I.  INTRODUCTION. 

The  element  tellurium  is  not  so  rare  as  is  general - 

(D 

ly  supposed.  A recent  estimate  of  the  amount  of  tellurium  that 

the  United  States  can  produce,  without  making  any  material  addi- 

(2,3,4) 

tions  to  present  plants,  is  125,000  lbs.  annually.  There 

is  little  market  for  tellurium  and  a corresponding  small  produc- 
tion, only  one  or  two  refineries  reporting  production  or  sale  of 
the  element.  Tellurium,  like  selenium,  is  a by-product  of  the  e- 
lectrolytic  refining  of  copper.  The  domestic  production  is  capa- 
ble of  large  expansion  if  market  conditions  should  warrant,  as 
almost  all  blister  copper  contains  recoverable  quantities  of  tel- 
lurium. Much  of  this  would  be  saved,  if  a demand  existed,  at 
prices  of  §1.50  to  §2,50  per  lb.  In  1917,  prices  at  the  refin- 
ery averaged  §3*00  per  lb.,  but  a very  small  additional  output 
would  probably  have  flooded  the  market. 

The  chemical  characteristics  of  tellurium  are  much 
like  those  of  sulfur,  but  as  would  be  expected  in  an  element  of 
higher  atomic  weight,  it  is  more  metallic.  Tellurium  looks  much 
like  antimony.  It  is  silver-white  and  so  crystalline  that  it  is 
quite  brittle  and  can  be  powdered.  Toward  acids  it  is  as  refrac- 
tory as  antimony;  toward  alkaline  solutions  it  is  strongly  re- 
sistant, while  in  water  or  moist  air  it  does  not  rust  or  corrode 
appreciably.  A consideration  of  these  properties  led  to  the  idea 
that  tellurium  might  be  used  as  an  alloying  material  to  make  met- 
als more  resistive  to  corrosion. 

Although  the  literature  on  the  subject  reveals  the 
preparation  of  several  tellurium  alloys,  no  studies  have  been 


2 


made  as  to  their  corrosion  resisting  power.  Pushin  prepared 
several  alloys  by  fusing  together  weighed  amounts  of  the  pure  met- 
als under  a layer  of  potassium  chloride  and  lithium  chloride  (to 
prevent  oxidation) , and  pouring  the  melt  into  molds  of  chalk  or 
magnesium  oxide.  The  alloys  of  silver  and  tellurium  were  black, 
crystalline,  harder  than  either  component,  but  very  brittle. The 
properties  of  the  copper- tellurium  alloys  varied  greatly  with 

composition.  When  rich  in  copper,  they  were  dark  gray,  crystal- 

tellurium 

line,  and  brittle;  with  30  to  33%/[  they  became  much  darker  and 
more  brittle;  with  more  than  33%  tellurium,  they  were  violet  in 
color,  and  with  more  than  50 $,  they  were  golden  brown.  Two  com- 
pounds, Cu2Te  and  CuTe,  formed  solid  solutions  with  each  other. 
Alloys  with  lead,  containing  50$  tellurium,  were  gray,  granular, 
and  brittle;  PbTe  formed  solid  solutions  with  lead  but  not  with 
tellurium.  Brittleness  and  a coarse  grained  structure  also  char- 
acterized the  tin-tellurium  alloys.  The  investigator  proved  the 
existence  of  the  compounds  Ag2Te,  Cu2Te,  PbTe,  and  SnTe. 

Two  Japanese  scientists,  Chikashige  and  Nose,  give 
give  reports  of  work  done  on  aluminium- tellurium  alloys.  Since 
tellurium  and  aluminium  unite  with  explosive  violencewhen  neated 
together,  the  tellurium  was  first  fused  in  a porcelain  tube  and 
the  aluminium  gradually  added.  Two  compounds  were  formed,  Te-jAl2, 
and  Te^Al5*  Te^Alg*  which  melted  at  895C,  formed  solid  solutions 
with  tellurium  up  to  4.4$  tellurium.  The  two  compounds  were  rap- 
idly decomposed  by  water,  and  evolved  a disagreeable  poisonous 

gas  H0Te,  which  rapidly  decomposed  into  tellurium  and  hydrogen. 

(7) 

Henry  Pay  found  that  tin  and  tellurium  united  to 
form  a compound  SnTe,  which  melted  at  769°*  This  compound  formed 


f • 


1 

. 

t 

3 


with  tellurium  a eutectic  which  melted  at  399°,  and  consisted  of 
85$  tellurium  and  15$  tin.  With  tin  the  compound  also  formed  a 
eutectic,  but  the  solution  of  SnTe  in  tin  was  so  low  that  it  was 
impossible  to  locate  the  concentration.  The  melting  point  of  the 
eutectic  of  low  concentration  appeared  to  be  the  same  as  that  of 
pure  tin. 

(3) 

J.  K.  Rose  has  established  a complete  freezing 
point  curve  for  varying  concentrations  of  gold  and  tellurium.  The 
curve  showed  one  compound  AuTe2,  with  a melting  point  of  452°. 

This  compound  formed  a eutectic  with  tellurium,  containing  20$ 
gold  and  melting  at  397°;  with  gold  it  formed  a eutectic  contain- 
ing 60$  gold,  melting  at  432°. 

(9) 

Kimata  states  that  only  one  compound  of  antimony 
and  tellurium  exists,  the  formula  being  Sb2Te^  and  the  melting 
point  620°.  This  compound  formed  with  antimony  a eutectic  melting 
at  540^  and  containing  27"28$  tellurium;  and  with  tellurium  a eu- 
tectic melting  at  420^,  containing  a little  under  90$  tellurium. 

(10) 

The  melting  point  curves  worked  out  by  H.  Pela- 
bon  showed  the  existence  of  Sb2Te-3(m.p.600('') , SnTe (m.p. 780°) , 
Bi2Te^(m. p. 583°) , PbTe(m. p.860^) , AgTe(m.p.955°) , and  Au2Te4(m.p. 
472°). 

(11) 

Ransom  and  Thieme  conceived  the  idea  that  tellur- 
ium might  be  used  as  a hardener  for  lead  and  other  metals.  When 
pure  lead  was  melted  and  tellurium  sprinkled  on  it,  the  tellurium 
glowed,  and  large  lumps  were  formed,  mixed  with  a coarse  powder 
which  floated  as  a dross.  Upon  separating  the  lumps  from  the  powder 
the  former  were  found  to  be  hard,  somewhat  malleable,  and  to  con- 
tain bo tn  lead  and  tellurium.  Tellurium  could  not  be  found  in  the 


4 


yellow  powder  and  its  nature  has  not  been  established.  Some  pure 
tin  bars  were  melted  and  poured,  and  after  removing  from  the  heat 
tellurium  was  added  in  powder  form  and  stirred  in.  No  glowing  was 
observed  but  a dross  appeared  on  the  surface.  The  alloy  contained 
1.12 % tellurium,  was  slightly  harder  than  pure  tin,  and  the  ten- 
sile strength  had  increased  from  3800  to  4265  lbs.  per  sq.  in. 
Similar  experiments  we re  performed  with  zinc  and  aluminium,  but 
only  traces  of  tellurium  were  found  in  the  treated  metal,  most  of 
it  being  in  the  dross;  however  the  tensile  strength  was  increased ' 
from  4955  to  5510  lbs.  per  sq.  in.  in  the  case  of  zinc,  and  from 
13840  to  14810  lbs.  per  sq.  in.  for  aluminium.  The  hardness  was 
not  changed. 

( 12) 

Fay  and  G-illson  have  also  made  investigations 
with  regard  to  lead- tellurium  alloys.  The  composition  of  the  al- 
loy of  maximum  freezing  point  corresponds  with  the  proportions 
of  the  metals  in  PbTe.  Lead  easily  became  supersaturated  witn 
PbTe,  which  separated  out  at  the  higher  freezing  point,  and  the 
lower  freezing  point  then  corresponded  to  the  solidification  of 
lead.  When  still  more  tellurium  was  present,  PbTe  again  separated 
at  the  higher  temperature,  but  the  lower  freezing  point  corres- 
ponded with  the  complete  solidification  of  the  alloy,  which  was 
a eutectic  of  PbTe  and  tellurium.  7/hen  examined  microscopically 
the  eutectic  could  be  seen  interspersed  between  the  crystals  of 
lead  or  tellurium,  according  to  which  was  present  in  excess.  Al- 
loys containing  more  than  50%  tellurium  were  very  brittle. 

This  sums  up  very  briefly  the  greater  part  of 
the  work  which  has  been  done  along  this  line.  The  resistance  of 
tellurium  to  the  action  °f  acids  and  alkalies  led  to  the  present 


5 


investigation  as  to  the  corrosion  of  lead- tellurium  alloys,  with 

a small 

the  hope  that  the  addition  of^percentage  of  tellurium  would  make 
the  lead  more  resistive  to  corrosion,  without  making  it  too  brit- 
tle for  its  ordinary  uses. 


6 


II.  Experimental  Work. 

Since  the  brittleness  of  the  lead- tellurium  alloy 
increases  rapidly  with  increase  in  the  percentage  of  tellurium, 
no  attempt  was  made  to  use  more  than  10$  of  the  latter,  a 10$ 
alloy  being  too  brittle  to  serve  the  purposes  for  which  lead  is 
ordinarily  used.  The  amounts  of  lead  and  tellurium,  correspond- 
ing to  the  various  percentages  of  tellurium  desired,  were  care- 
fully weighed  out,  into  clay  crucibles  ana  morougnly  mixed,  un 
account  of  the  ease  with  whi ch  tellurium  volatilizes  and  oxi- 
dizes, the  mixture  was  then  covered  with  a layer  of  charcoal  be- 
fore fusion.  A gas  furnace  furnished  a sufficiently  high  temper- 
ature for  the  fusion,  since  the  melting  points  of  lead  and  tel- 
lurium are  respectively  327(">  and  4-5 1*“*.  After  fusion  for  twenty 
minutes,  the  mixture  was  allowed  to  cool  and  the  charcoal  was 
removed  from  the  top;  sufficient  heat  was  then  applied  to  melt 
the  alloy,  so  that  it  could  be  poured  into  a graphite  mold,  form 
ing  strips  of  fairly  uniform  surface.  The  mold  consisted  of  two 
plates  of  graphite,  clamped  tightly  together;  on  the  inner  sur- 
face of  one  of  them  a rectangular  depression  about  two  and  one 
half  inches  long,  three -fourths  of  an  inch  wide,  and  one-eigth 
of  an  inch  deep  had  been  cut  by  a chisel.  Some  difficulty  was 
experienced  in  getting  a smooth  surface  on  the  strips  contain- 
ing the  higher  percentages  of  tellurium.  This  was  overcome  by 
sandpapering. 

For  the  corrosion  tests,  the  alloys  were  first 
weighed  and  then  placed  in  nitric  acid  (.01  and  .1  molal),  also 
in  hydrochloric  acid  (.1  molal),  and  in  sulfuric  acid  (.1  molal) 


7 


for  successive  periods  of  five  days  each.  After  each  period  the 
strips  were  removed,  cleaned,  dried,  and  weighed  before  replacing 
in  the  acids  on  the  shaking  machine.  The  shaking  machine  served 
to  agitate  the  solutions  sufficiently  so  that  they  should  not 
form  saturated  layers  around  the  alloys.  From  the  loss  in  weight, 
the  per  cent  of  corrosion  was  calculated.  The  greatest  difficul- 
ty encountered  in  these  tests  was  to  remove  the  corrosion  com- 
pletely or  at  least  equally  from  the  strips,  especially  in  the 
case  of  the  .01  molal  nitric  acid,  where  a yellowish-white  pre- 
cipitate always  formed  and  clung  tenaciously  to  the  surface.  This 
precipitate  upon  analysis  seemed  to  contain  no  tellurium,  and  was 
probably  a basic  nitrate  of  lead,  which  formed  due  to  the  great 
dilution  of  the  nitric  acid.  Best  results  were  obtained  by  sim- 
ply removing  the  corrosion  by  means  of  a brush,  except  in  the 
case  of  the  sulfuric  acid,  where  it  was  necessary  to  place  the 
strips  in  sodium  acetate  solution  for  equal  lengths  of  time  in 
order  to  remove  the  lead  sulfate.  In  all  probability  this  diffi- 
culty in  removal  of  corroded  material  caused  the  discrepancies 
which  will  be  seen  in  the  results.  However,  since  in  general  the 
relationships  were  the  same  between  successive  five  day  periods, 
fairly  representative  results  were  obtained  by  averaging  the  per- 
centages of  corrosion,  and  plotting  these  averages  against  the 
composition. 

No  curve  is  shown  for  the  results  with  sulfuric 

acid  because  the  values  obtained  were  very  irregular.  This  is  due 

no  doubt,  as  said  before,  to  the  very  slight  action  of  sulfuric 

acid  on  lead  and  to  the  unequal  removal  of  corrosion.  The  curve 

•• 

for  .01  molal  nitric  worked  out  well  and  showed  an  increased  re- 


8 


sistance  with  increase  of  tellurium  present.  Some  irregularities 
are  seen  in  the  curves  for  . 1 molal  nitric  acid  and  . 1 molal  hy- 
drochloric acid,  especially  in  the  case  of  the  former,  where  there 
is  a very  marked  increase  in  corrosion  for  alloys  containing  ,07% 
and  . 09 % of  tellurium.  This  is  probably  due  to  experimental  error 
but  it  is  possible  that  another  compound  of  lead  and  tellurium 
is  formed.  In  general,  the  presence  of  tellurium  seems  to  lessen 
the  corrosion  to  a slight  extent. 


■ 


9 


III. RESULTS. 

Per  cent  of  Corrosion  in  .01  Molal  HNO3. 


1 . 

2. 

3- 

4. 

5.  6 

7. 

8 . Av. 

Pb 

1.0376 

1.0000  1 

.1880  1. 

0397  0. 

9999  0.9895  0.9995 

1.0395  1.0367 

1$Te 

0.7794 

0.6648  0 

.7760  0. 

6322  0. 

7118  0.9137  0.8984 

0.9566  0.7919 

2$Te 

0.8102 

0.5828  0 

.7751  0. 

6513  0. 

7443  0.8239  0.8953 

0.9550  0.7798 

3/aTe 

0.5965 

0.4365  0 

.5702  0. 

5923  0. 

7313  0.6875  0.7040 

0.6317  0.6250 

Per  cent 

of  corrosion  in 

. 1 Molal 

HNO3 . 

1. 

2. 

3. 

4. 

5. 

6. 

Av. 

Pb 

1.3220 

2.0549 

1.6117 

1 .6363 

1 .6944 

2.3291 

1 .7744 

. 06^Te 

1.0400 

1 .9161 

1.4355 

1.5804 

1-7842 

2.2569 

1 .6683 

. 07;^Te 

2.4290 

2.9415 

3.277 6 

3 . 1 406 

3*2975 

3.5313 

3.1112 

. 09/^Te 

2.5000 

2. 6105 

2.9663 

3.0241 

3.2492 

3.2956 

2.9409 

. lO^Te 

1.2790 

2.5608 

1.41 1 1 

1 . 2947 

1.7881 

2.0616 

1.7325 

. 30;^Te 

1.3000 

2.6532 

1 . 5334 

1.5620 

1.6139 

1.9704 

1 .7708 

. 50^Te 

1.2110 

2.6463 

1.5200 

1.6163 

1 . 5488 

2.0132 

1.7592 

.SO^Te 

1.6920 

1.3639 

1.5950 

1 .6337 

2.5569 

1.7783 

1$Te 

1 .6629 

1.3398 

1.3528 

1 .3245 

2.2585 

1.6877 

2/^Te 

1.651 1 

1.3943 

1 .4443 

1.9058 

2. 1360 

1 .7063 

5/o  Te 

1.7840 

2,2813 

1 .8191 

1.7641 

2.3293 

2 . 7045 

2.  1 137 

8;^Te 

2.1550 

2.9483 

2.0399 

2. 1373 

2.7031 

3.2356 

2.5382 

lO^Te 

3. 1780 

3.2662 

2.3101 

2.0669 

2.9671 

3.8926 

2.7775 

10 


Per  cent  of  corrosion 

1.  2.  3- 

in  .1  Molal  HG1 . 

4.  3. 

Av. 

Pb 

0. 1001 

0.5924 

0.5381 

0.7277 

0.5633 

0.5144 

. 06$Te 

0.0931 

0.4024 

0.5613 

0.5764 

0.5254 

0.4317 

.07foTe 

0.0993 

0.4107 

0.5397 

0.5478 

0.6255 

0.4466 

. 2QfoTe 

0. 1342 

0.4937 

0.6030 

0.6067 

0.7006 

0.5076 

.40$Te 

0.0621 

0.3497 

0.4901 

0.5894 

0.5302 

0.4043 

.80%Te 

0.0982 

0.4302 

0.5062 

0.5814 

0.6010 

0.4434 

1 .OO^Te 

0.0992 

0.3932 

0.5165 

0.5241 

0.5141 

0.4094 

2. 20%Te 

0. 1225 

0.4126 

0.5457 

O.6166 

0.6231 

0.4641 

6.70/oTe 

0. 1301 

0.4525 

0.6354 

0.3438 

0.7039 

0.5531 

Per  cent  of  corrosion 

ill  . 1 Molal  H2S04. 

1 . 

2. 

3. 

4. 

Av. 

Pb 

0.01 16 

0.0156 

0.0058 

0 . 0097 

0.0107 

,07^Te 

0.0083 

0.0264 

0.0059 

0.0177 

0.0146 

. 2Q^Te 

0.0069 

0.0108 

0.0000 

0.0079 

0.0064 

.40^Te 

0.0000 

0.0099 

0.0000 

0.0119 

0.0055 

• SO.^Te 

0.0184 

0.0160 

0.0100 

0.0020 

0.0116 

A 

» 

0 

0 

1-3 

CD 

0.0000 

0.0060 

0.0040 

0.0041 

0.0035 

1 1 


3%TC- 


3%Tc- 


/%T e- 


°fo  Corrosion  i. n .ot  moLaL  K NO^ 


12 


6.7  %Te^ 


l^cTe.  - 


/‘VoTe.  i 
8 7oTe  - 

■7*re.  - 

-?7oTe  i 
>77  oTe.— » 
>6  7 oTe  - 

Pb-  "" 


7o  Co 


i~roS(.on 


l n .1  m o Ul 


14 

IV. 

Attempt  to  Analyze  a Lead-Tellurium  Mixture. 

The  separation  and  quantitative  determination  of 
tellurium  from  a mixture  of  lead  and  tellurium  presents  several 
difficulties,  such  as  the  formation  of  lead  tellurate,  the  vola- 
tility and  oxidation  of  tellurium,  occlusion  of  sulfur  etc.,  de- 
pending upon  the  method  used.  The  following  methods  were  tried: 

1 . A mixture  of  lead  and  tellurium  was  evaporated 
just  to  dryness  with  nitric  acid,  forming  lead  nitrate  and  tel- 
lurium dioxide,  which  upon  treatment  with  sodium  hydroxide  dis- 
solved to  form  sodium  plumbite  and  sodium  tellurite.  Hydrogen 
sulfide  was  then  used  to  precipitate  the  lead  as  lead  sulfide, 
the  sodium  tellurite  remaining  in  solution.  T/Then  the  latter  was 
acidified  and  hydrogen  sulfide  again  passed  in,  the  tellurium 
was  precipitated  as  metallic  tellurium,  which  was  filtered  off, 
evaporated  to  dryness  with  nitric  acid,  and  ignited  gently  to 
tellurium  dioxide . 

Pb"\  Ph(  1103)2^  Na2Pb02\  PbS 

[ HNOdv  l NaQIL  HoS  . HOl.HpSs  HNQ? 

Te  f ~ ~Te02  [ ^Na2Te03  | *?Na2Te03  1 Te~  *Teq 

The  determination  was  not  at  all  successful  owing  probably  to  the 

volatility  of  tellurium  dioxide. 

2.  The  procedure  was  carried  out  the  same  as  in  1, 
as  far  as  the  separation  and  formation  of  tellurium  dioxide.  This 
was  then  dissolved  in  sodium  hydroxide,  forming  sodium  tellurite, 
oxidized  to  sodium  tellurate  by  sodiun  peroxide,  and  precipitated 
as  barium  tellurate  by  the  addition  of  barium  chloride. 


15 


Pb' 


Te 


NaOH  v 

' NapTeO-2 


Na2Pb0c 


TeOp 


The  barium  tellurate  was  ignited  and  weighed,  but  in  every  case  the 
weight  was  much  too  high.  This  might  be  accounted  for  by  the  fact 
that  there  must  be  a large  amount  of  sulfur  precipitated  with  the 
tellurium,  and  this  sulfur  would  be  oxidized  to  a sulfate  and  be 
precipitated  as  barium  sulfate  along  with  the  barium  tellurate.  The 
possibility  of  occlusion  is  also  great.  The  use  of  hydrogen  perox- 
ide as  an  oxidizing  agent  gave  the  same  results. 

3.  The  method  which  promised  to  give  the  best  re- 
sults was  the  standard  method  of  precipitation  by  sulfur  dioxide 
in  hydrochloric  acid  solution.  The  mixture  of  lead  and  tellurium 
was  evaporated  to  dryness  with  nitric  acid  and  the  products  dis- 
solved in  sodium  hydroxide,  forming  sodium  plumbite  and  sodium  tel- 
lurite. Upon  acidifying  with  hydrochloric  acid,  most  of  the  lead 
precipitated  as  lead  chloride  and  was  filtered  off.  When  sulfur  di- 
oxide was  then  passed  into  the  solution,  the  tellurium  came  down  as 
the  element,  and  was  filtered,  dried,  and  v/eighed. 


Pb)  Pb(N03)s 


TeOo 


- - I 


16 


V.  Summary. 

1.  When  exposed  to  the  action  of  .01  molal  nitric  acid, 
alloys  of  lead  and  tellurium  seem  to  show  an  increase  of  resist- 
ance to  corrosion  with  increase  of  tellurium  present. 

2.  Alloys  of  lead  and  tellurium  containing  from  .06$ 
to  5 % tellurium,  with  the  exception  of  the  .07$  and  .09$  alloys, 
show  a slightly  greater  resistance  to  the  action  of  . 1 molal  ni- 
tric acid  than  does  lead. 

3.  Pure  lead  is  corroded  more  by  . 1 molal  hydrochlor- 
ic acid  than  are  its  alloys  with  tellurium,  containing  up  to  4.8$ 
of  the  latter. 

4.  The  results  indicate  that  in  general  tellurium  in- 
creases the  resistance  of  lead  to  . 1 molal  sulfuric  acid;  however 
these  results  are  very  irregular  and  unreliable  on  account  of  un- 
equal removal  of  corroded  material. 

5.  Tellurium  is  probably  best  determined  quanti tative- 
ly  by  reduction  to  metallic  tellurium  by  sulfur  dioxide  in  hydro- 
chloric acid  solution,  after  filtering  off  the  lead  chloride.  The 
tellurium  is  then  dried  and  weighed. 


17 


VI.  Bibliography. 

1.  Lenher,V. J.  Ind.  and  Eng.  Chem. , 12.597-3 . 

2.  Umpleby, J.B. Min.  Res.  of  U.S.,1917. 

3.  Hill, J.M. U.S.Geol. Survey,  1913. 

4.  Loughlin,G.F.  and  Clark, Martha  B.^-* Min. Res.  of  U.S.,1919. 

5.  Pushin,N.A. J. Russ. Ph.vs. Ghem. Soc.  .39. 13-54. 

6.  Chikashige,M.  and  Nose,J.--- Mem. Coll . Sci .Kyoto  Imp.  Univ. 

2,227-32. 

7.  Fay, Henry------  J. Am. Chem. Soc . .29. 1265-8. 

8.  Rose, T. K. ------  Trans. Inst. Min. Metal . Brit. . 17. Pt. 1 , 285-9 • 

9.  Kimata,Y. -J.  Soc  ♦ Chem.  Ind.  .34.1211. 

10.  Pelabon,H. Ann. Chem. Phys. , JLZ»  526-66 . 

11.  Ransom, J.H.  and  Thieme, C.O. Chem. and  Met. .25. 102. 

12.  Fay,  Henry  and  Gill  son,  C . B. Arne  r.  Chem. -J.  .27.81-95. 


18 


VII.  Acknowledgment. 

The  writer  hereby  wishes  to  acknowledge  her  indebted- 
ness and  to  extend  her  thanks  to  Dr.  B.S. Hopkins,  under  whose 
direction  this  work  was  done. 


